The invention herein relates to an improved tennis court playing surface. Tennis court surfaces are commonly made of a compacted layer of clay material, or of asphalt, or concrete or the like. Grass or turf surfaces also have been used. But because of the expense and the degree of care required, grass courts have mostly disappeared from use, although still used for certain tennis matches.
Another type of tennis court surface is formed of a synthetic carpet covered with granular material. An example of such a surface is described in U.S. Pat. No. 4,044,179, issued to Haas on Aug. 23, 1977. In this type of court, a flat under-surface or support surface is formed on the ground, usually with suitable drain provisions. Then, the under surface is covered with a so-called "outdoor" synthetic fiber or pile carpet. This, in turn, is covered with layers of granular material which provide, along with the tips of the carpet strands, where same are exposed, a playing surface.
In this type of carpet, the strands or fibers or piles are fastened, either by tufting or by direct fastening, to a base or backing sheet which may be formed of a woven material with or without a rubber-like backing layer, secured to the woven material.
In the synthetic carpet type of playing surface, as described in the above patent, the carpet has been covered by multiple layers of granular material. That is, a fine sand layer is laid directly upon the base sheet, around the strands. A coarse sand layer is applied over the fine sand layer. In addition, a moisture retention material, such as vermiculite or the like, is included either as a separate layer or mixed with the sand, in order to retain a pre-determined amount of moisture to hold the sand against shifting. However, the use of multiple layers, particularly of different grain sizes, and the additional moisture retention materials, increases expenses because of increased difficulty in applying and maintaining the surface for long periods of time, particularly where the court is exposed to extreme changes in weather conditions as is common in many parts of the world where tennis is played.
Thus, the invention herein is concerned with improving the above mentioned type of tennis court surface. More specifically, this invention is concerned with providing a stabilized sand-type of playing surface which is somewhat resilient to provide the ball rebound and speed characteristics that are generally found in clay-type courts, but wherein the application of the sand surface is simplified and the sand is stabilized against permanent shifting or wind blowing.